Selective and complete repairs are the main methods of performing repair works to eliminate pipelines corrosion and stress-corrosion defects. The advantages of both methods are compared, both from a technical and economic standpoint, and from the point of view of the organization and production of large-scale construction and installation works.
Initially, at the stage of operation of the first main gas pipelines, their overhaul was carried out exclusively with a complete replacement of pipes. Subsequently, with the development of in-line diagnostics, a more rational approach to the choice of a repair method — began to develop selective repair of the pipelines with the accumulation of the main efforts on defective pipe sections found a widespread use. This is due to the fact that the diagnostic examinations showed an uneven level of technical condition of pipes and sections along the length of gas pipelines. However, complete repair with replacement of pipes still makes up a significant part of the total volume of repair operations.
The issues of planning repair work are considered from the point of view of optimization of organizational and operational costs. The principle of optimal planning of work should be based on minimizing the functional of the total costs of the repair itself, and on compensating for the shortage of gas to consumers during the period of its implementation.
Analysis of the technical condition of the main gas pipelines showed that there is no need for large-scale repair work on the overwhelming majority of the lines in the central and southern directions, therefore, selective repair should be adopted as the main one, contributing to the functional cost minimization. The calculation results show that the efficiency of selective repairs application depends on the number of single sections, the organization of simultaneous work at the object, and the number of relocations of the columns and crews. Due to the heterogeneity of the pipelines technical condition, the selective method of carrying out repair works in many cases becomes the most efficient. In this case, the choice of technology and organizational scheme for the work production should be determined based on the specific conditions at the repair site.
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